ISSN:
1432-0967
Source:
Springer Online Journal Archives 1860-2000
Topics:
Geosciences
Notes:
Abstract Geochemical patterns in two, correlative, Ordovician, basaltic greenstone formations from the central Norwegian Caledonides corroborate field indications of a tripartite stratigraphic subdivision of the units. Lower and upper members show similar chemical traits and are transitional to LREE-enriched, high-magnesia to low-magnesia basalts. The thicker, more massive, middle member carries the geochemical signature of LREE-depleted, ‘normal’ mid-oceanic ridge tholeiites. Stratigraphic-upward petrochemical variation discerned within the individual members points to processes of either closed or open-system low-P fractional crystallization. The geochemical trends can be ascribed to a mechanism of spreading accompanied by lithospheric thinning in a marginal ocean basin situation, followed by renewed crustal thickening. Geochemical and lithovolcanic polarity indicators denote that the basin was located to the east of an Arenig-Llanvirn magmatic arc sited within the Caledonian Iapetus Ocean.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00518118
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